Year	% of total fuel combustion
1971	10.617551462621885
1972	8.368200836820083
1973	6.95742471443406
1974	9.090909090909092
1975	8.448117539026628
1976	7.777777777777778
1977	8.8659793814433
1978	7.901554404145078
1979	5.606166783461808
1980	6.36986301369863
1981	4.689480354879595
1982	6.071220081727963
1983	3.6809815950920246
1984	3.8028169014084505
1985	3.766816143497758
1986	3.800475059382422
1987	3.7103746397694524
1988	3.675048355899419
1989	3.6453506333024404
1990	3.8138138138138142
1991	3.6720044174489237
1992	3.559155621011291
1993	3.3804121324380647
1994	4.610318331503842
1995	4.737130339539978
1996	4.825432869713313
1997	5.18925518925519
1998	3.982621288921071
1999	4.228520017993702
2000	4.561229548834903
2001	4.971042471042471
2002	5.732801595214357
2003	5.722961924783929
2004	5.91542410168663
2005	4.185821437212678
2006	4.017013232514178
2007	3.8610038610038617
2008	3.96732788798133
2009	3.6115916955017298
2010	3.95332221957609
2011	3.6152497808939525
2012	3.614992237746728
2013	3.5179153094462547
2014	3.358364622444723